Hopeful Signs for rufa Red Knots – including “B-95” seen again!

The past year has apparently been a good one for the rufa subspecies of Red Knots (Calidris canutus rufa). This is welcome news for a subspecies that has experienced sharp and severe population declines since 2000, and has been classified as Endangered in Argentina and by the Committee on the Status of Wildlife in Canada, and is a candidate for Endangered Species listing in the United States.

The first sign of good news began after the 2008 Arctic breeding season, when high numbers of male knots (identified with molecular techniques in Dr. Allan Baker’s lab) were seen at the Mingan Archipelago of Quebec, Canada, in August. The date of their occurrence strongly suggests that these were birds that bred successfully rather than leaving in an earlier wave with failed breeders. This impression was reinforced by the aerial survey finding by Guy Morrison and Ken Ross that the population “wintering” (in the austral summer!) in Tierra del Fuego had increased by about 3,000 individuals—the first uptick in many years. On-the-ground teams in both the Argentine and Chilean parts of Tierra del Fuego found a good number of juveniles, completing the picture of a successful breeding season and resulting recruitment to the population.

Shorebird superstar “B-95”, now 17 years old, was seen again this May in Delaware Bay, New Jersey! (Pictured here in winter plumage in Argentina)/Courtesy of Patricia González

Patricia González’s teams that were monitoring the migration along the coast of Patagonia found knots in excellent condition as they moved northward. Two individual knots stunned everyone by being seen in Florida by Pat and Doris Leary only 13 days after they were last seen in San Antonio Oeste, Argentina. The straight-line distance (which would involve an undocumented crossing of the Andes) would be about 7,800 kilometers; a more likely coastal route would involve traveling some 10,000 kilometers. This is the first hard evidence that knots move north without significant stopovers and is the result of intensified banding and resighting efforts made at an international scale over recent years.

An emotional side of the banding work came about at Delaware Bay (New Jersey) this May when Luís Benegas of Argentina, working with Allan Baker and Patricia González, resighted “B-95,” the same adult Red Knot he banded in Río Grande, Tierra del Fuego (Argentina), in 1995! B-95 is now at least 17 years old and continues to inspire us—and our supporters!

Red Knots and other shorebirds feast upon Horseshoe Crab eggs at Delaware Bay, New Jersey, before continuing their migration to Arctic breeding grounds./© Patricia González

Good news from the crucial Delaware Bay stopover doesn’t stop there. The large international team working there, led by Larry Niles and Mandy Dey, found that more knots made their “threshold weights” of 180 grams than in a decade. At this weight, their probability of continued survival and successful breeding in the Arctic is high. Moreover, the knots left Delaware Bay several days earlier than in past years—another sign that they were in strong condition and ready to travel and breed. 

Horseshoe Crab eggs are the major food source to migrating knots at Delaware Bay. While it is tempting to hope that restrictions on the harvest of Horseshoe Crabs have had an effect, this is likely premature. Favorable weather for the crabs’ spawning—at last—was surely a major contributing factor.